Electric heating device.



J. A. HEANY.

ELECTRIC HEATING DEVICE.

APPLlcATIoN HLED Nov. 12, 1914.

WW r m ew J. A. HEANY. ELECTRIC HEATING DEVlce.

APPLICATION HLED N0V.12I 1914.

Patented Nov. 6, 1917.

2 sHETs-sHEET 2.

, being then conducted UNITED STATES PATN FFICE.

`JOHN.ALLEN HENY, OF NEW YORK, N. Y., ASSIGNOR TO PATENTS EXPERIMENT CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC HEATING DEVICE.

Application filed November 12, 1914.

To aZZ whom t may concem:

Be it known that I, JOHN ALLEN Hna'xr, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Electric Heating Devices; and I do hereby declare the following to be a full,`clear, and exact vdescription of the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

The invention relates to electric heating devices such as sad irons, cookers and the like, designed to employ alternating or pulsating currents in a coil or induction element associated with 'the heating unit, which induce eddy currents and hysteresis effects in the body portion of the heating unit. These eddy currents and the hysteresis du'e to reversals of magnetism in turn develop heat which it is desired to utilize in the heating unit.

It has been the customary practice heretofore to supply the heat for said irons, electric stoves and the likev by means of heating coils associated therewith, in which the heat was developed as the result of the ohmic resistance of the coils, the heat so developed to the metal of the heating unit proper. Attempts have also been made to employ alternating current suppliedto a suitable coil, which is intended to generate eddy currents in the body of the heating unit and also to develop the hysteresis efi'ect therein, both of which contribute to the development of heat in the unit BothA systems as heretofore practised, however, have met with more or less objection i on the ground of lack of economy in the 85 unit consumption of electric energand also because of the liability of the irect heating coils to burn out or to produce short circuits. In the case of old types of heating units employing alternating currents, lack of economy in current consumption, uneven heating and general uncertainty of operation have seriously militated against the general use of such devices. I The present invention is designed, however, to p,rovide a heating unit, which is simle in construction, certain in operation and liighly economic-al and eificient in convertin the electric energy into heat. To this en' the invention contemplates a heating in which the body portion is made of a Specification of Letters 'atent.

rent, or, in other words,

Patented Nov,I 6, 1917.

serial No. 871,711

mmetal having the capability of developing high hysteresis and eddy current efiects, such for example as cast iron, which body portion is provided with a recess, in which is located the inducing coil, which is mounted upon a core of metal, preferably in the form of assembled laminae, possessing high magnetic perrneability, such as steel, which core is fitted in said recesses between opposing walls forme-d in said body portion, the ends of said core being in contact with said walls so that two complete magnetic circuits are formed through the body of the heating unit and the core aforesaid, the course of said magnetic circuits being generally circular whereby a substantiall'y uniform heating of the body of the unit results. A typical development of the invention is illustrated in the accompanying drawings, in which, I

Figure 1 is a side elevation of a sad iron having the invention applied thereto.

Fig. 2 is a Vertical longitudinal section of the iron.

Fig. 3 is a plan view of the body portion lof the iron.

Fig. 4 is a side clevation of the said body portion.

Fig. 5 is an end view thereof.

Figs. 6 and 7 are side elevation and end view of the laminated core and spool for the coil.

Fig. 8 is a plan view of the spool with the coil applied thereto.

As indicated, in developing the present invention, particular attention has been given to c'idevising an electric heating unit which will produce the most heat with the lowest possible consumption of exciting curto develop a heating unit with a high power factor. As exemplifying a simple and effective form of the invention, the same has been illustrated as applied to a sad iron in which the body portion 1 is of a generally triangular shape in plan view, provided with a fiat lower or working surface having a basal fiange E2 extending laterally from the body portion, which latter has a central .recess or depression 8, likewise of a generally triangular Shape which results in the body portion assumihg the Shape of an inclosing wall sur-l rounding a central well or recess, which latter is closed at the bottom by the metal of the working face of the iron. The body portion 1 on opposite sides of the recess 3 is provided with two enlargements or bosses 4, the interior faces of which are finished or inachined to form two substantially parallel opposing surfa-Ces 5 extending from the bottom of the recess 3 to a short distance above the top of the bodv portion 1, as shown in Figs. 3, 4; and 5. The structure as thus defined is preferably made of cast iron because of its high hysteresis loss and also because its temperature Coeflicient of resistance is nearly zero, which has the desirable effect of maintaining the current consumption by the eddy Currents substantially Constant when starting and during normal operation.

Fitting snugly within the recess 3 between the opposing surfaces 5 is a spool or bobbin 10 adapted to carry the primary coil, which conveys the alternating current. Said spool or bobbin is preferabljr formed with a core 12 made of superposed laminae of sheet steel, which because of its high permeability admits of the magnetic fiug: density being quite high without undue increase of the exciting Current. The ends of the core 12 are iianked by face plates 11 which closely engage the opposed faces 5 of the projections 4 in the body portion 1. Closely surrounding the core 12 is a coil 11 of wire covered by a fireproof or heat-resisting insulating medium, such as asbestos or the like, one end of the wire being carried through an opening 13 in one of the face plates 11 and thence upward through a groove 6 in face 5 of one of the bosses or projections 4.

It is highly desirable, on account of the Cost to keep the amount of wire in the coil as low as possible, and this result is materially assisted by the shape and Character of the core 12. By the use of steel in the core, a high magnetic flux density may be realized, with the result that each turn of wire in the coil may be made shorter, which makes for economy in copper or other metal of which the coil may be formcd. By laminating the steel core, eddy current losses in the same, which tend to raise the temperature of the coil and to lessen the total fiux because of uncqual distribution, are largely avoided.

Inclosing the upper portion of the body 1 and the coil 10 is a cover 15, preferably of aluminum, which is secured to the body portion by means of screws or bolts 17, which engage threaded recesses 7 in the body portion, as Clearly indicated in Figs. 1 and 2. The rear portion of the cover is provided with a hollow extension 18 through which the lead wires pass to the coil 14, and to the upper portion of said hollow extension, there is secured a handle 19 by means of a bolt- 20 provided with a screw-threaded end engaging a threaded socket in said extension.

VVith an iron constructed in accordance with the illustration and description just referred to, having an outside length of approximately six inches and a width of about four inches, with a core of approXirn-ately one inch in diameter and one inch long surrounded by about 175 turns of No. 19 gage asbestos-covered copper wire, a substantiall uniform heat can be maintained indefinitely upon the ordinary commercial 110 Volt alternating current Circuit, without any danger of over-heating of the iron or blowing the line fuses. As thus Constructed, the sad iron is in effect a transformer, the primary of which is constituted by the coil 111 and the secondary by the metal of the body portion l and the core 12 of the bobbin or spool carrying the coil. This secondary also constitutes a. double magnetic cii'cuit in which the lines Of magnetic fiux flow in a horizontal direction and in a generally Circular path through the front portion of the body portion and the magnetic core 12 on the one hand, and through the rear portion of the body portion and the core on the other hand. By this arrangement, substantially uniform eddy current and hysteresis effects are produced throughout the entire body portion of the iron with a resultant uniform transformation and distribution of heat in and to all parts of the iron.

VVhat I elaim is 1. An electric heating unit employing alternating or pulsating currents, comprising a body portion of metal having high hysteresis and eddy current loss factors provided with a recess having two opposed walls, a core of metal possessing high permeability located in said recess with its end surfaces abutting said walls, the body portion and the core constituting the closed secondary of a transformer and a double 106 magnetic Circuit and an exciting coil covered with heat resisting insulation on said core, the parts being so Constructcd and arranged that the current consumed in the eXCiting` coil is substantially Constant at all 110 temperatures and the power factor of Current consumed is substantially unity.

2. An electric heating unit employing alternating` or pulsating currents, comprising a body portion of cast iron. provided 115 with a recess having two opposed walls, a Core of steel located in said recess With its end surfaces abutting said walls, the body portion and the core constituting the closed secondary of a transformer and a double 120 magnetic Circuit and an exciting coil covered with heat resisting insulation on said core, the parts being so constructed and arranged that the current consumed in the cxciting coil is substantially Constant at all 125 temperatures and the power factor of current consumed is substantially unity.

3. An electric hcating unit employing alternating or pulsating currents, comprising a body portion of cast iron provided 130 with a recess having two opposed walls, a laminated vsteel core located in said'recess withits end surfaces abutting said walls, the body portion and the, core constituting the closed secondary of a transformer and a double magnetic circuit and an exciting coil covered with heat resisting insulation on said core, the parts beingV so construct'ed and arranged that the current consumed in the excitingzcoil is substantially constant at all temperatures and the power'factor of current consumed is substantially unity.

4;. An electric heating unit employing alternating or pulsating currents, comprising a cast iron body portion provided with a recess within continuous walls provided with two opposed faced Sections, a laminated steel core located between said faced Sections and having its end surfaces in abutting' engagement therewith, the body portion and the core constituting the closed secondary of a transformer and a double magnetic circuit and an exciting coil covered with the heat resisting insulation on said core, the parts being so constructed and arranged that the current consumed in the exciting coil is substantially constant at all temperatures and the power factor of current consumed is substantially unity. i

In testimony whereof I aflix my signature, in presence of two witnesses.

JOHN ALLEN HENY. Witnesses: I

FEED. B. MAGLAREN, Viom B. SMITH. 

